Rate-dependent response of excavations and permanent underground structures

Research Project, 2021 – 2024

As cities expand, the depth and extent of excavations and underground structures in urban
areas will likely increase e.g. as a result of societal shift towards sustainable modes of transportation. The
complexity of excavations increases further due to strict regulations on the allowable deformations in the vicinity.
Such restrictions during the construction phase not only affect the earth pressures in the short-term, but also may
affect the long-term earth pressures against the permanent structure.
The main aim of this project is to develop conceptual models and design charts for earth pressure against
permanent structures in clay. The main objective is to replace design based on over-simplified methods (such as
K0-factor design) with normalised earth pressure charts based on sound numerical studies. The scope of work
entails analyses of measurement data from “part 1” of a PhD-project (Tornborg, 2020). Numerical studies are
carried out to generalise the results of site-specific data. The results are presented as normalised diagrams
contributing to results that are scalable e.g. varying geometries, construction time, relative wall-soil stiffnesses.
The knowledge from the project increases the understanding for which variables that substantially influence the
development of earth pressure. This utilises sound design methods leading to reduced uncertainty and optimisation
of construction material volumes for earth retaining and permanent underground structures.